1. Field of the Invention
The present invention relates to a method of and an apparatus for controlling vehicle speed. More particularly, the invention relates to the method of and the apparatus for automatically controlling the moving speed of a vehicle at the target speed with improved precision.
2. Description of Related Art
Typically, an art related to a method of and an apparatus for automatically correcting the traveling distance and the traveling speed of a vehicle was previously proposed in the Japanese Laid-Open Patent Publication No. 54-95277 of 1979 for example. This prior art is provided with a vehicle speed detector which generates pulses in response to the running speed of a vehicle, the distance computed by integrating pulses corresponding to the actual speed of the vehicle between the predetermined positions being compared with the distance between the predetermined positions, and then computes the corrective coefficient before eventually correcting the vehicle speed.
An automatic train drive control unit disclosed in the Japanese Laid-Open Patent Publication No. 50-103010 of 1975 comparatively computes the number of pulses outputted from a speed generator while the train runs through the reference distance against the reference pulse number determined in accordance with the reference distance, and then on the basis of the actual diameter of wheels of the train yielded from the result of computation, the above train drive control system corrects the data of the wheel diameter in order that the traveling speed of the train can be corrected.
According to the method of and the apparatus for the automatic correction of the traveling distance and speed of a vehicle or the automatic train drive control unit cited above, the moving speed of a vehicle or a train can be controlled at a specific level. Nevertheless, neither of these prior arts can properly solve speed error caused by variable load on the part of the vehicle or the train. More particularly, both of these prior arts merely corrects the moving speed or the data on the diameter of wheels of the vehicles by solely comparing the distance between the predetermined positions (or the pulse number determined by the reference distance) with the distance (or the number of pulses outputted during this period), and thus, even when the traveling speed is variable by variation of load caused by deviation from the predetermined distance or from the reference distance, neither of these prior arts could properly correct the varied speed. Accordingly, there is a problem that each of the vehicles cannot be moved at a constant speed and pitch in the case where each load of a plurality of non-connected vehicles vary.